1. Field of the Art
This invention relates to the manufacture of optical glass elements of predetermined shape from elongated glass rods, and more particularly to a jig for use in washing optical glass elements which are obtained by polishing glass rods and cutting same into predetermined unit lengths for optical elements.
2. Prior Art
Manufacturing processes of optical glass elements such as cylindrical lenses, for example, usually include polishing and cutting stages. More specifically, after polishing surfaces of elongated glass rods to a predetermined profile or curvature, the polished glass rods are cut into unit lengths for optical elements to be produced. A polishing tray 1 as shown in FIG. 8 is usually employed in these operational stages. The polishing tray 1 is formed of stainless steel and provided with a plural number of parallel rows of rod holder blocks 3 of inverted T-shape in cross section to support thereon glass rod 4, each in a space between adjacent rows of rod holder blocks 3. The glass rods 4 are supported on the rod holder blocks 3 while surfaces of the respective glass rods 4 are being polished. Each row of the rod holder blocks 3 has a length which is substantially the same as or larger than that of the glass rod 4, and the spacings between the adjacent rows of the support blocks 3 substantially conform with the width of the glass rods 4. The height of the rod holder blocks 3 is smaller than the thickness of the glass rods 4.
The glass rods 4 on the above-described polishing tray 1 must be held in a fixed state to prevent spontaneous movements during a polishing operation. For this purpose, as indicated in phantom in FIG. 8, the lower side of each glass rod 4 which is seated on stepped land portions 3a of the holder blocks 3 is fixedly bonded to the latter by the use of wax of the like. After the polishing operation, the glass rods 4 are cut into unit lengths at positions as indicated by broken lines in FIG. 8 according to dimensions of ultimate optical products. For cutting the glass rods 4 on the polishing tray 1, a number of cutting slits 5 are provided in the rod holder members 3 at predetermined intervals in the longitudinal direction. These cutting slits 5 are cut into the rod holder ridges 3 from upper side and at least to a depth in level with the stepped land portions 3a.
After polishing and cutting the glass rods 4, the optical elements come out with smudged or dusty surfaces bearing polishing powder or dust of removed material in addition to spots of wax or an adhesive which was used for fixation of glass rods 4. Accordingly, it is the general practice to wash the optical elements by ultrasonic cleaning subsequent to the shaping process, thereby getting rid of the adhesive or other organic substances. For this purpose, it becomes necessary to transfer the shaped optical elements on the polishing tray to a washing rack or the like. In order to separate and remove the optical elements from the polishing tray 1, the adhesive power of the adhesive agent, which was used in fixing the glass rods 4 to the polishing tray in the cutting stage, is destroyed before the transfer by heating the polishing tray 1 on a hot plate to a temperature at which the adhesive agent is melt down and fused. Then, the optical elements are picked up from the polishing tray one after another and put on a jig for a washing or cleaning operation. In so doing, it has been the usual practice to pick up and transfer optical elements manually by the use of tweezers or pincer of bamboo or other soft-touching tool which would not damage the optical elements.
However, since the glass rods on the polishing tray have been cut into a large number of units of optical elements, this job of transferring optical elements manually one by one in that manner is extremely troublesome and time consuming. Especially, for enhancing the efficiency of the manufacturing process, each polishing tray is constructed in a compact form and arranged to carry as many glass rods as possible. Therefore, the glass holder ridges which intervene the respective glass rods are very small in width or thickness, and optical elements on the polishing tray are arrayed densely with only a small spacing between adjacent optical elements. Accordingly, meticulous skill is required for picking up optical elements by inserting tweezers into narrow spacings, making the job more difficult and troublesome.
In addition, the adhesive is used for fixing glass rods on a polishing tray tentatively and should not have such a strong adhesive power as to make it difficult to remove optical elements in a later stage. Therefore, the reaction forces which act on the respective glass rods in the polishing and cutting stages should be born not by the adhesive but by the vertical walls of the glass holder ridges in contact with the opposite sides of the glass rods. For this purpose, the glass holder ridges are required to have a sufficient height, which is a little short of the top side of the glass rods. This gives rise to another problem that only limited surface areas on lateral sides of each optical elements are accessible by tweezers or the like, making it difficult to hold the optical element stably on tweezers when picking it up from a polishing tray. Consequently, there are many possibilities of the optical elements slipping off or being dropped off when picked up from the polishing tray or while in transfer therefrom. Since optical glass elements are fragile, they can be fractured or damaged easily even by slight impact.